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festerbot3000
22-06-2010, 04:41 PM
I know that for a given Pressure you have a given temperture. What i need help with is the math formula top get to the temperture with a given pressure. I'm trying to write a PLC program and need this forumla. I have tryed google and all i came up with was the chart. I need the math behind the chart. Thanks for your help

NoNickName
22-06-2010, 04:51 PM
Pick 10 points, put them in excel, regress the curve, export the coefficient of the polynomial.

festerbot3000
22-06-2010, 04:56 PM
We have tried that and it works for temperature to pressure. It doesn't seem to work for pressure to temperature. Thanks for the response. Any further help would be great!

NoNickName
22-06-2010, 06:52 PM
It depends whether you are in a single phase or two phase area of the state diagram.

piewie
14-08-2010, 11:30 PM
Hello Festerbot

Did you ever suceed with this calculation? I do have a mitsi plc with the program installed but it was never really good as there were times that it was so inaccurate that the superheat was negative. If you did suceed can you help me with this?

Sandro Baptista
15-08-2010, 10:57 AM
Maybe you need more points...Do you want covered superheat and subcooling regions or only saturated temperatures?